The Basal Ganglia Over 500 Million Years.
Level 5 - mechanism / opinion, no new human data
Narrative review of comparative animal neurobiology and theoretical synthesis
PubMed 27780050 · doi:10.1016/j.cub.2016.06.041
What was done
The authors reviewed comparative neuroanatomical, neurochemical, and physiological findings comparing the basal ganglia of the phylogenetically basal vertebrate lamprey with mammalian (rodent and primate) models to trace circuit evolution.
What was found
The abstract reports no numerical values or statistical metrics. Qualitatively, it states that inputs from the pallium/cortex and thalamus, intrinsic organization, output projections, transmitters, connectivity, and membrane properties are virtually identical between lamprey and rodent basal ganglia. It describes conserved direct (D1-expressing striatal projection neurons disinhibiting brainstem motor centers) and indirect (D2-expressing striatal projection neurons suppressing motor activity) pathways alongside phasic dopamine input.
Why it matters
This synthesis demonstrates that the foundational blueprint of basal ganglia circuits evolved over 500 million years ago, suggesting that the expansion of complex vertebrate behaviors occurred via duplicating and adapting conserved ancestral modules rather than developing novel circuit architectures.
Limits
The abstract describes a narrative review and theoretical framework without systematic search methodology or quantitative data. The conclusions rely on comparative animal models and mechanistic inferences regarding ancestral evolutionary states.
Cited by
- supports The basal ganglia are evolutionarily conserved deep brain nuclei dating back to the lamprey roughly 360 million years ago.